The present invention relates broadly to apparatus for grinding and finishing the metal edge of a workpiece and, more particularly, pertains to a modified, portable, power tool for sharpening the side edges of a ski.
It is common practice today to provide a biting edge to snow skis and snowboards by use of a metal strip along each side at the bottom corners. Each strip is flush with the base of the ski, but extends slightly out from the sides of the ski. This edge provides a surface to cut into the snow, and adds to the maneuverability. For a ski or snowboard to carve an arc on hard or icy snow surfaces without sliding, it is necessary to have as sharp an edge as possible.
With use, these edge surfaces often become dented or otherwise dulled and it becomes necessary to sharpen them. Presently, machines and tools are available to flat finish the base of the ski, but it becomes much more difficult to accomplish proper sharpening along the sides of the ski. Often, the sharpening is done by skilled personnel carrying out ski sharpening services in association with the sale of skis and related equipment. To maintain the sharp edge surfaces, the sides of the ski or snowboard are normally hand-filed, which is a slow process and requires experience to perform the task with a high level of skill.
An owner may manually sharpen his/her own skis if a suitable tool is available for doing so. A known tool is designed with a short metal file set in an L-shaped holder provided with an angle plate for changing the sharpening angle of the file. The user moves the holder along the ski edge with the file contacting the side edge while a guide plate slides along the base of the ski. Other types of hand held or hand operated ski sharpening tools are available but all are generally extremely labor intensive to use and do not produce acceptable results.
Electrically operated ski sharpeners are also known in which a grinding wheel or disc is driven by an electric motor which is manually slid along the base of the ski. Although guide devices are included in these designs, the vibration and lack of proper stabilization of the motor tends to affect the quality and uniformity of the ski sharpening. In at least one of these motorized ski sharpeners, a device is included to change the disposition of the ski so as to vary the sharpening angle or xe2x80x9cbackcutxe2x80x9d on the side edges. However, it appears that the maintaining of this angle is not always satisfactory.
In addition to the need to sharpen the side edge of a ski or snowboard that has become dented or dulled, many ski and snowboard racers change the backcut angle of their side edges depending upon the snow/ice conditions of the race course. The backcut may vary from a 2xc2x0 angle to as much as 7xc2x0, depending upon the conditions. A backcut with a greater angle, such as 2xc2x0-7xc2x0, will become dull at an increasingly fast rate. Thus, if a racer wishes to maintain the proper backcut angle, the side edges must be sharpened at a much greater frequency.
It would be desirable to provide an improved ski sharpening arrangement which alleviates the drawbacks of manually and motor operated ski sharpeners such that a consistent, accurate and efficient grinding of the side edges of the ski are easily obtainable and lead to optimized stability and performance for the skier. It is desirable to provide a ski sharpening arrangement mainly intended for a serious racer and ski technician such that the racer or technician can sharpen a ski prior to a race. It is desirable to provide an improved ski sharpening arrangement that includes inexpensive and replaceable grinding surfaces which are easy to replace and exchange.
It is a general object of the present invention to provide an arrangement for guiding, stabilizing and changing the angle of a movable abrasive surface on a powered belt grinder for sharpening the side edge of a ski.
It is also an object of the present invention to provide a ski sharpening arrangement for protecting the base of the ski during sharpening of a ski side edge.
It is a further object of the present invention to provide a portable, powered belt grinder modified with a support structure which is particularly applicable for on-site sharpening of skis by an owner thereof.
It is an additional object of the present invention to provide a ski sharpener having a motor which is held spaced from the ski during operation to avoid problems caused by excess vibration.
It is another object of the present invention to provide a ski sharpening arrangement which will provide and maintain accurate backcutting in. the sharpening of a ski side edge and the plastic bonding and support of the metal edge.
In one aspect of the invention, the ski sharpening arrangement includes a portable, powered grinder adapted to be manipulated by one hand of a user and including a motor assembly spaced from a ski having a top surface, a base, a side edge and a bottom edge coplanar with the base. The motor assembly drives an endless belt having an abrasive surface about an axis of rotation transverse to a plane of the base. The endless belt is entrained about a mounting framework extending from the motor assembly and is engaged against the side edge of the ski to provide sharpening thereof. A support structure is suspended from the mounting framework of the belt and is adapted to be manipulated by another hand of the user for guiding, stabilizing and changing the angle of the abrasive surface relative to the side edge of the ski.
In a preferred embodiment, the mounting framework includes a channcl-shaped member having an upper wall, a lower wall and a connecting wall joining the upper and lower walls. The lower wall has a belly portion for guiding the abrasive surface of the belt into an area of contact with the side edge of the ski. The connecting wall defines a mounting surface for attaching the support structure to the powered grinder. The support structure includes a roller assembly coupled with a movable adjustment device having a pair of sidewalls, a front wall joining the sidewalls and the top wall connecting the sidewalls and the front wall. The roller assembly includes a generally U-shaped holder having a first leg and a second leg joined to a bight portion. The roller assembly further includes a guide roller rotatably mounted on the holder for movement against and along the base of the ski. The guide roller has an outer peripheral surface formed with a series of annular grooves for holding a plurality of 0-rings therein. The guide roller has an internal wall defining a passageway for receiving a shaft held fixed relative to the holder. A set of bearings is positioned between the internal wall of the guide roller and the shaft so that the guide roller rotates relative to the fixed shaft. A stabilizing handle adapted to be manipulated by another hand of the user is secured to the bight portion of the holder. The shaft has one end which projects into a fixed sleeve having one extending beyond the top wall of the adjustment device. The one end of the sleeve is provided with an indicator plate. One of the sidewalls is secured to the connecting wall of the mounting framework. An L-shaped reinforcing bracket is placed between the one sidewall and the connecting wall. The front wall of the adjustment device is formed with a lower circular opening, an upper slotted opening and a pointed indicator. A lower fastener is passed through the lower circular opening and partially threaded into the sleeve. An upper fastener is passed through the upper slotted opening and threaded into the sleeve. With this construction, selected manipulation of the upper and lower fasteners enables a tilting of the adjustment device relative to the sleeve, and causes an angular adjustment of the abrasive surface of the belt relative to the side edge of the ski. The adjustment device is located adjacent the mounting framework of the powered grinder and above the side edge of the ski. The O-rings on the guide roller are maintained against the base of the ski by applying a force on the handle in a direction transverse to a rotational axis of the guide roller. An indicator on the front wall of the adjustment device is movable relative to the indicator plate on the sleeve when the adjustment device is tilted relative to the sleeve.
Various other objects, features and advantages of the invention will be made apparent from the following description taken together with the drawings.